iommu: Move default domain allocation to iommu_probe_device()

Well, not really. The call to iommu_alloc_default_domain() in
iommu_group_get_for_dev() has to stay around as long as there are
IOMMU drivers using the add/remove_device() call-backs instead of
probe/release_device().

Those drivers expect that iommu_group_get_for_dev() returns the device
attached to a group and the group set up with a default domain (and
the device attached to the groups current domain).

But when all drivers are converted this compatability mess can be
removed.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200429133712.31431-9-joro@8bytes.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -79,6 +79,16 @@ static bool iommu_cmd_line_dma_api(void)
 	return !!(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API);
 }
 
+static int iommu_alloc_default_domain(struct device *dev);
+static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
+						 unsigned type);
+static int __iommu_attach_device(struct iommu_domain *domain,
+				 struct device *dev);
+static int __iommu_attach_group(struct iommu_domain *domain,
+				struct iommu_group *group);
+static void __iommu_detach_group(struct iommu_domain *domain,
+				 struct iommu_group *group);
+
 #define IOMMU_GROUP_ATTR(_name, _mode, _show, _store)		\
 struct iommu_group_attribute iommu_group_attr_##_name =		\
 	__ATTR(_name, _mode, _show, _store)
@@ -221,10 +231,29 @@ int iommu_probe_device(struct device *dev)
 		goto err_free_dev_param;
 	}
 
-	if (ops->probe_device)
+	if (ops->probe_device) {
+		struct iommu_group *group;
+
 		ret = __iommu_probe_device(dev);
-	else
+
+		/*
+		 * Try to allocate a default domain - needs support from the
+		 * IOMMU driver. There are still some drivers which don't
+		 * support default domains, so the return value is not yet
+		 * checked.
+		 */
+		if (!ret)
+			iommu_alloc_default_domain(dev);
+
+		group = iommu_group_get(dev);
+		if (group && group->default_domain) {
+			ret = __iommu_attach_device(group->default_domain, dev);
+			iommu_group_put(group);
+		}
+
+	} else {
 		ret = ops->add_device(dev);
+	}
 
 	if (ret)
 		goto err_module_put;
@@ -268,15 +297,6 @@ void iommu_release_device(struct device *dev)
 	dev_iommu_free(dev);
 }
 
-static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
-						 unsigned type);
-static int __iommu_attach_device(struct iommu_domain *domain,
-				 struct device *dev);
-static int __iommu_attach_group(struct iommu_domain *domain,
-				struct iommu_group *group);
-static void __iommu_detach_group(struct iommu_domain *domain,
-				 struct iommu_group *group);
-
 static int __init iommu_set_def_domain_type(char *str)
 {
 	bool pt;
@@ -1423,25 +1443,18 @@ static int iommu_get_def_domain_type(struct device *dev)
 	return (type == 0) ? iommu_def_domain_type : type;
 }
 
-static int iommu_alloc_default_domain(struct device *dev,
-				      struct iommu_group *group)
+static int iommu_group_alloc_default_domain(struct bus_type *bus,
+					    struct iommu_group *group,
+					    unsigned int type)
 {
 	struct iommu_domain *dom;
-	unsigned int type;
-
-	if (group->default_domain)
-		return 0;
 
-	type = iommu_get_def_domain_type(dev);
-
-	dom = __iommu_domain_alloc(dev->bus, type);
+	dom = __iommu_domain_alloc(bus, type);
 	if (!dom && type != IOMMU_DOMAIN_DMA) {
-		dom = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_DMA);
-		if (dom) {
-			dev_warn(dev,
-				 "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA",
-				 type);
-		}
+		dom = __iommu_domain_alloc(bus, IOMMU_DOMAIN_DMA);
+		if (dom)
+			pr_warn("Failed to allocate default IOMMU domain of type %u for group %s - Falling back to IOMMU_DOMAIN_DMA",
+				type, group->name);
 	}
 
 	if (!dom)
@@ -1461,6 +1474,23 @@ static int iommu_alloc_default_domain(struct device *dev,
 	return 0;
 }
 
+static int iommu_alloc_default_domain(struct device *dev)
+{
+	struct iommu_group *group;
+	unsigned int type;
+
+	group = iommu_group_get(dev);
+	if (!group)
+		return -ENODEV;
+
+	if (group->default_domain)
+		return 0;
+
+	type = iommu_get_def_domain_type(dev);
+
+	return iommu_group_alloc_default_domain(dev->bus, group, type);
+}
+
 /**
  * iommu_group_get_for_dev - Find or create the IOMMU group for a device
  * @dev: target device
@@ -1491,16 +1521,26 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
 	if (IS_ERR(group))
 		return group;
 
+	ret = iommu_group_add_device(group, dev);
+	if (ret)
+		goto out_put_group;
+
 	/*
 	 * Try to allocate a default domain - needs support from the
 	 * IOMMU driver. There are still some drivers which don't support
-	 * default domains, so the return value is not yet checked.
+	 * default domains, so the return value is not yet checked. Only
+	 * allocate the domain here when the driver still has the
+	 * add_device/remove_device call-backs implemented.
 	 */
-	iommu_alloc_default_domain(dev, group);
+	if (!ops->probe_device) {
+		iommu_alloc_default_domain(dev);
 
-	ret = iommu_group_add_device(group, dev);
-	if (ret)
-		goto out_put_group;
+		if (group->default_domain)
+			ret = __iommu_attach_device(group->default_domain, dev);
+
+		if (ret)
+			goto out_put_group;
+	}
 
 	return group;